Fatal error: Uncaught Error: Class 'Drupal\Core\Plugin\DefaultPluginManager' not found in /var/www/html/tmp/contrib/simple_oauth/src/Plugin/Oauth2GrantManager.php:27 Stack trace: #0 {main} thrown in /var/www/html/tmp/contrib/simple_oauth/src/Plugin/Oauth2GrantManager.php on line 27